Perhaps you should try some spelling variations:
hoc sach » hoc cac, hoc anh
viet cua » viec cua, viet ca, viet qua
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
ve cac » va cac, vien cac
lo van » le van, vo van, do van
so van » su van, vo van

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((hoc sach) OR (hoc sinh)) ky nang xa hoi. hieu ve cac ((lo van) or (so van)) anh viet cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc sach) OR (hoc sinh)) ky nang xa hoi. hieu ve cac ((lo van) OR (so van)) anh viet cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc sach) OR (hoc sinh)) ky nang xa hoi. hieu ve cac ((lo van) or (so van)) anh viet cua tre".
• Adding a wildcard symbol may retrieve word variants: ((hoc sach) OR (hoc sinh)) ky nang xa hoi. hieu ve cac ((lo van) or (so van)) anh viet cua tre*.